Bifurcated graft with a superior extension

ABSTRACT

A bifurcated graft is formed from a series of individual components which are intraluminally delivered apart from one another and then assembled to form a fully supported structure. The modular system includes a base member and one or more grafts connected thereto. The base member preferably includes a portion which gradually increases in diameter. A tubular device for inserting the components of the modular system and a method employing the modular system for repairing an abdominal aortic aneurysm are also disclosed.

This application is a continuation of U.S. application Ser. No.09/365,638, filed Aug. 3, 1999, now U.S. Pat. No. 6,416,542 which is acontinuation of U.S. application Ser. No. 08/840,406, filed Apr. 29,1997, now U.S. Pat. No. 5,993,481, which is a divisional of U.S.application Ser. No. 08/393,701, filed Feb. 24, 1995, now U.S. Pat. No.5,683,449.

FIELD OF THE INVENTION

The present invention relates to bifurcated intraluminal grafts,particularly for repairing defects in arteries and other lumens withinthe body. More particularly, the present invention relates to modularsystems for forming bifurcated grafts and to methods for delivering andassembling same in situ for repairing defective body lumens, andparticularly abdominal aortic aneurysms.

BACKGROUND OF THE INVENTION

An abdominal aortic aneurysm is a sac caused by an abnormal dilation ofthe wall of the aorta as it passes through the abdomen. The aorta is themain artery of the body, supplying blood to all organs and parts of thebody except the lungs. It arises from the left ventricle of the heart,passes upward, bends over and passes down through the thorax and throughthe abdomen, and finally divides into the two iliac arteries whichsupply blood to the pelvis and lower extremities.

The aneurysm ordinarily occurs in the portion of the aorta below thekidneys. When left untreated, the aneurysm will eventually cause the sacto rupture with ensuing fatal hemorrhaging in a very short time. Therepair of abdominal aortic aneurysms has typically required majorabdominal surgery in which the diseased and aneurysmal segment of theaorta is removed and replaced with a prosthetic device, such as asynthetic graft.

As with all major surgeries, there are many disadvantages to theforegoing surgical technique, the foremost of which is the highmortality and morbidity rate associated with surgical intervention ofthis magnitude. Other disadvantages of conventional surgical repairinclude the extensive recovery period associated with such surgery;difficulties in suturing the graft to the aorta; the loss of theexisting thrombosis to support and reinforce the graft; theunsuitability of the surgery for many patients, particularly olderpatients exhibiting co-morbid conditions; and the problems associatedwith performing the surgical procedure on an emergency basis after theaneurysm has already ruptured.

In view of the foregoing disadvantages of conventional surgical repairtechniques, techniques have been developed for repairing abdominalaortic aneurysms by intraluminally delivering an aortic graft to theaneurysm site through the use of a catheter based delivery system, andsecuring the graft within the aorta using an expandable stent. Since thefirst documented clinical application of this technique was reported byParodi et al. in the Annals of Vascular Surgery, volume 5, pages 491-499(1991), the technique has gained more widespread recognition and isbeing used more commonly. As vascular surgeons have become moreexperienced with this endovascular technique, however, certain problemshave been encountered. One problem has been the difficult nature of theprocedure. Particularly complex is the step of transferring one leg ofthe graft from one iliac artery to the other, which requires the carefulmanipulation of numerous catheters and guide wires. Another problem hasbeen the kinking and/or twisting of the graft both during and after thegraft has been implanted. Still other problems relate to the need foraccurate preoperative measurements to be made on the morphology of theaneurysm and the surrounding arterial structure, including the length ofthe aneurysm, the infrarenal aortic length and diameter, the length anddiameter of the aorta between the aneurysm and the iliacs, the diameterof the iliacs, and the angle between the iliacs and the aorta. Thedifficulty in making these measurements accurately and the widevariations in these measurements among patients mandates that thebifurcated grafts be available in a wide range of sizes andconfigurations.

There therefore exists a need for a bifurcated graft and an implantationmethod which will overcome the foregoing deficiencies of the prior art.More particularly, there exists a need for a modular graft system whichwill more accurately accommodate the widely varying arterial sizes inpatients, as well as the other size considerations faced by the surgeon.There also exists a need for a method for delivering and implanting abifurcated graft which avoids the complex procedure for implanting priorart bifurcated grafts.

SUMMARY OF THE INVENTION

The present invention addresses the needs.

One aspect of the present invention provides a modular prosthesis forrepairing a tubular anatomical structure consisting of a base memberfoldable radially between a collapsed configuration and an expandedconfiguration and extending longitudinally between a proximal end and adistal end, a primary tubular limb foldable radially between a collapsedconfiguration and an expanded configuration and having a proximal endand a distal end, and joining means for intraluminally joining thedistal end of the primary limb to the proximal end of the base member.Preferably, the joining means includes a friction fit engagement betweenthe distal end of the primary limb in the expanded configuration and theproximal end of the base member in the expanded configuration.

In accordance with one embodiment of the modular prosthesis, the primarylimb may have a first diameter at its proximal end and a second diameterless that the first diameter at its distal end. In this regard, thediameter of the primary limb may decrease from the proximal end towardthe distal end at an angle of taper between about 2 degrees and about 15degrees. In preferred embodiments, the primary limb may have a diameterat its proximal end of between about 16 mm and about 36 mm in theexpanded configuration and a diameter at its distal end of between about16 mm and about 25 mm in the expanded configuration. The primary limbmay also have a length from its proximal end to its distal end ofbetween about 6 cm and about 15 cm. Desirably, the primary limb includesan annular sleeve at its distal end, the annular sleeve having asubstantially uniform diameter. The primary limb may also includesecuring means at its proximal end for securing the primary limb to thetubular anatomical structure.

The base member may have a first diameter at its proximal end and asecond diameter greater than the first diameter at its distal end. Inpreferred embodiments, the base member may have a diameter at itsproximal end of between about 16 mm and about 25 mm in the expandedconfiguration. The base member may also include an annular sleeve at itsproximal end, the annular sleeve having a substantially uniformdiameter. Preferably, the annular sleeve has a length between about 2 cmand about 15 cm.

The base member and the primary limb may both consist of a flexiblelayer which is radially supported along substantially its entire lengthby an expandable stent. In one embodiment, the expandable stent may beformed from a high shape-memory material. In another embodiment, theexpandable stent may be formed from a low shape-memory material.

In accordance with another embodiment hereof, the base member mayinclude dividing means for forming first and second passagewayscommunicating between the proximal and distal ends of the base member.The dividing means may include a line of stitching joining one surfaceof the base member to an opposite surface of the base member.Alternatively, the dividing means may include a web of material arrangedlongitudinally inside the base member and defining a first substantiallyround aperture adjacent the distal end of the base member and a secondsubstantially round aperture at a spaced distance from the distal end ofthe base member. Preferred embodiments may further include at least onesecondary tubular limb foldable radially between a collapsedconfiguration and an expanded configuration and having a proximal endand a distal end, and connecting means for connecting the proximal endof the secondary limb to the distal end of the base member.

In accordance with a further embodiment of the present invention, amodular prosthesis for repairing a tubular anatomical structure consistsof a base member foldable radially between a collapsed configuration andan expanded configuration and having a proximal end and a distal end, aprimary tubular limb foldable radially between a collapsed configurationand an expanded configuration and having a proximal end and a distalend, joining means for intraluminally joining the distal end of theprimary limb to the proximal end of the base member, at least onesecondary tubular limb foldable radially between a collapsedconfiguration and an expanded configuration and having a proximal endand a distal end, and connecting means for connecting the proximal endof the secondary limb to the distal end of the base member. Thesecondary limb may have a substantially uniform diameter of betweenabout 10 mm and about 25 mm in the expanded configuration.Alternatively, the proximal end of the secondary limb may have adiameter which is different than the diameter on its distal end.Preferably, the secondary limb has a length between its proximal end andits distal end of between about 4 cm and about 15 cm.

In this last embodiment, the base member may include a main leg on itsproximal end and first and second legs on its distal end. The main legmay extend in an axial direction and have a main passageway extendinglongitudinally therein and defining an inlet on its free end. The firstleg may be oriented at a first angle to the axial direction and have apassageway extending longitudinally therein and communicating with themain passageway, and may define a first outlet on its free end. Thesecond leg may be oriented at a second angle to the axial direction andhave a passageway extending longitudinally therein and communicatingwith the main passageway, and the second leg may define a second outleton its free end. The first angle may be different than the second angle,but each of the first and second angles are preferably between about 10degrees and about 60 degrees. Also, the main leg may be oriented in aprimary plane, and at least one of the first and second legs may beoriented in a plane different than the primary plane.

In a variant of this last embodiment, the base member may include acrotch defined between the first and second legs, the first leg having alength between the crotch and the first outlet of between about 2 cm andabout 15 cm. Preferably, the first leg has a substantially uniformdiameter of between about 10 mm and about 25 mm in the expandedconfiguration, and the second leg has a diameter which decreases in sizefrom the second outlet toward the main leg.

This last embodiment may further include another secondary tubular limbfoldable radially between a collapsed configuration and an expandedconfiguration and having a proximal end and a distal end, and attachingmeans for attaching the proximal end of the another secondary limb tothe distal end of the base member. The another secondary limb may have alength between its proximal end and its distal end of between about 4 cmand about 15 cm, and a substantially uniform diameter of between about10 mm and about 25 mm in the expanded configuration. Alternatively, theanother secondary limb may have a first diameter at its proximal end anda second diameter at its distal end different than the first diameter.

In yet another embodiment of the present invention, a modular prosthesisfor repairing a tubular anatomical structure may consist of a basemember extending longitudinally between a proximal end defining an inletand a distal end defining first and second outlets, the base memberbeing foldable radially between a collapsed configuration and anexpanded configuration, and a primary tubular limb having a proximal endand a distal end and being foldable radially between a collapsedconfiguration and an expanded configuration. The distal end of theprimary limb in the expanded configuration may be matable in overlappingcircumferential engagement with the inlet of the base member when thebase member is in the expanded configuration to join the primary limb tothe base member. The modular prosthesis may also include at least onesecondary tubular limb having a proximal end and a distal end and beingfoldable radially between a collapsed configuration and an expandedconfiguration. The proximal end of the at least one secondary limb maybe matable in overlapping circumferential engagement with one of thefirst and second outlets of the base member when the base member is inthe expanded configuration to join the at least one secondary limb tothe base member. Another secondary tubular limb may also be provided inwhich its proximal end is matable in overlapping circumferentialengagement with another of the first and second outlets of the basemember when the base member is in the expanded configuration to join theanother secondary limb to the base member.

Another aspect of the present invention provides a prosthesis forrepairing a tubular anatomical structure consisting of a hollow tubularbody constructed from a woven fabric and having a length defined betweena first end and a second end, the first end having a first diameter andthe second end having a second diameter, the body having a diameterintermediate the first and second ends which is less than at least oneof the first and second diameters. The first diameter may also be lessthan the second diameter. The first end of the body may have a diameterbetween about 16 mm and about 25 mm and the second end of the body mayhave a diameter between about 16 mm and about 36 mm. The diameter of atleast a portion of the body may increase in size at an angle of taperbetween about 2 degrees and about 15 degrees, preferably at an angle oftaper of about 4 degrees. The body may also have a length between about6 cm and about 15 cm. Preferably, the body also includes an annularsleeve integrally formed at one end, the annular sleeve having asubstantially uniform diameter.

Preferred embodiments of this aspect of the present invention mayfurther include an expandable stent assembled to the body and radiallysupporting the body along substantially the entirety of its length. Theexpandable stent may be assembled in the interior of the body or on theexterior of the body, and may be formed from a high shape-memorymaterial or from a low shape-memory material.

Yet another aspect of the present invention provides a method forrepairing a tubular anatomical structure having a proximal branch and apair of distal branches projecting from the proximal branch at a pointof bifurcation. A method in accordance with this aspect of the presentinvention may include the steps of providing a first tubular limbfoldable radially between a collapsed configuration and an expandedconfiguration and having a proximal end and a distal end, providing abase member foldable radially between a collapsed configuration and anexpanded configuration and having an inlet and first and second outlets,and providing a primary tubular limb foldable radially between acollapsed configuration and an expanded configuration and having aproximal end and a distal end. The first limb may be fed in thecollapsed configuration through one distal branch until its proximal endis positioned adjacent the point of bifurcation and its distal end ispositioned within the one distal branch. The first limb may then beexpanded from the collapsed configuration to the expanded configurationwhereupon it engages and becomes secured within the one distal branch.

The base member may then be fed in the collapsed configuration throughthe one distal branch and the first limb until the inlet is positionedin the proximal branch, the first outlet is positioned within theproximal end of the first limb, and the second outlet is at leastpartially aligned with the other distal branch. The base member may thenbe expanded from the collapsed configuration to the expandedconfiguration, whereupon the first outlet engages the proximal end ofthe first limb in friction fit circumferential contact to join the firstoutlet of the base member to the first limb.

The primary limb may be fed in the collapsed configuration through oneof the distal branches and one of the first and second outlets of thebase member until its proximal end is positioned in the proximal branchand its distal end is positioned within the inlet of the base member.The primary limb may then be expanded from the collapsed configurationto the expanded configuration, whereupon its distal end engages theinlet in friction fit circumferential contact to join the primary limbto the inlet of the base member and its proximal end engages and becomessecured within the proximal branch.

Preferred methods may further include the steps of providing a secondtubular limb foldable radially between a collapsed configuration and anexpanded configuration and having a proximal end and a distal end,feeding the second limb in the collapsed configuration through the otherdistal branch until its proximal end is positioned within the secondoutlet of the base member and its distal end is positioned within theother distal branch, and expanding the second limb from the collapsedconfiguration to the expanded configuration, whereupon its proximal endengages the second outlet of the base member in friction fitcircumferential contact to join the second limb to the second outlet ofthe base member and its distal end engages and becomes secured withinthe other distal branch. The steps of feeding and expanding the secondlimb may occur prior to the steps of feeding and expanding the primarylimb.

Another method in accordance with the present invention may include thesteps of providing a base member foldable radially between a collapsedconfiguration and an expanded configuration and having an inlet andfirst and second outlets, and providing a primary tubular limb foldableradially between a collapsed configuration and an expanded configurationand having a proximal end and a distal end. The base member may be fedin the collapsed configuration through one of the distal branches untilthe inlet is positioned in the proximal branch, the first outlet ispositioned within the one distal branch, and the second outlet is atleast partially aligned with the other distal branch, and expanded fromthe collapsed configuration to the expanded configuration, whereupon thefirst outlet engages and becomes secured within the one distal branch.The primary limb may be fed in the collapsed configuration through oneof the distal branches and one of the first and second outlets of thebase member until its proximal end is positioned in the proximal branchand its distal end is positioned within the inlet of the base member.The primary limb may be expanded from the collapsed configuration to theexpanded configuration, whereupon its distal end engages the inlet infriction fit circumferential contact to join the primary limb to thebase member and its proximal end engages and becomes secured within theproximal branch.

This last method may further include the steps of providing a firsttubular limb foldable radially between a collapsed configuration and anexpanded configuration and having a proximal end and a distal end,feeding the first limb in the collapsed configuration through the otherdistal branch until its proximal end is positioned within the secondoutlet of the base member and its distal end is positioned within theother distal branch, and expanding the first limb from the collapsedconfiguration to the expanded configuration, whereupon its proximal endengages the second outlet of the base member in friction fitcircumferential contact to join the first limb to the second outlet ofthe base member and its distal end engages and becomes secured withinthe other distal branch.

A still further method for repairing anatomical structures in accordancewith the present invention may include the steps of providing a primarytubular limb foldable radially between a collapsed configuration and anexpanded configuration and having a proximal end and a distal end, andproviding a base member foldable radially between a collapsedconfiguration and an expanded configuration and having a proximal endand a distal end. The primary limb may be fed in the collapsedconfiguration through one distal branch until it is positioned entirelyin the proximal branch, and expanded from the collapsed configuration tothe expanded configuration, whereupon it engages and becomes securedwithin the proximal branch. The base member may be fed in the collapsedconfiguration through one distal branch until its proximal end ispositioned within the distal end of the primary limb, and expanded fromthe collapsed configuration to the expanded configuration, whereupon itsproximal end engages the distal end of the primary limb in friction fitcircumferential contact to join the base member to the primary limb. Inpreferred methods, the step of feeding the base member may include thestep of positioning the base member so that its distal end rests uponthe point of bifurcation when the base member is joined to the primarylimb.

In a variant of this last method, the base member may include first andsecond passageways providing communication between its proximal anddistal ends, and the method may include the further steps of providing afirst tubular limb foldable radially between a collapsed configurationand an expanded configuration and having a proximal end and a distalend, feeding the first limb in the collapsed configuration through onedistal branch until its proximal end is positioned within one passagewayof the base member and its distal end is positioned within the onedistal branch, and expanding the first limb from the collapsedconfiguration to the expanded configuration, whereupon its proximal endengages the one passageway of the base member in friction fitcircumferential contact to join the first limb to the base member andits distal end engages and becomes secured within the one distal branch.The method may further include the steps of providing a second tubularlimb foldable radially between a collapsed configuration and an expandedconfiguration and having a proximal end and a distal end, feeding thesecond limb in the collapsed configuration through the other distalbranch until its proximal end is positioned within the other passagewayof the base member and its distal end is positioned within the otherdistal branch, and expanding the second limb from the collapsedconfiguration to the expanded configuration, whereupon its proximal endengages the other passageway of the base member in friction fitcircumferential contact to join the second limb to the base member andits distal end engages and becomes secured within the other distalbranch.

Yet a further method for repairing a tubular anatomical structure inaccordance with the present invention may include the steps of providinga component foldable radially between a collapsed configuration and anexpanded configuration and having a proximal end with a first diameter,a distal end with a second diameter, and a diameter intermediate itsproximal and distal ends which is less than at least one of the firstand second diameters. The component may be fed in the collapsedconfiguration through one distal branch until it is positioned entirelyin the proximal branch, and expanded from the collapsed configuration tothe expanded configuration, whereupon the component engages and becomessecured within the proximal branch.

In this last method, the component may include first and secondpassageways providing communication between its proximal and distalends, and the method may include the added steps of providing a firsttubular limb foldable between a collapsed configuration and an expandedconfiguration and having a proximal end and a distal end, feeding thefirst limb in the collapsed configuration through one distal branchuntil its proximal end is positioned within one passageway of thecomponent and its distal end is positioned within the one distal branch,and expanding the first limb from the collapsed configuration to theexpanded configuration, whereupon its proximal end engages within theone passageway of the component in friction fit circumferential contactto join the first limb to the component and its distal end engages andbecomes secured within the one distal branch. Preferred methods mayfurther include the steps of providing a second tubular limb foldableradially between a collapsed configuration and an expanded configurationand having a proximal end and a distal end, feeding the second limb inthe collapsed configuration through the other distal branch until itsproximal end is positioned within the other passageway of the componentand its distal end is positioned within the other distal branch, andexpanding the second limb from the collapsed configuration to theexpanded configuration, whereupon its proximal end engages within theother passageway of the component in friction fit circumferentialcontact to join the second limb to the component and its distal endengages and becomes secured within the other distal branch.

The modular graft system and surgical methods of the present inventionovercome many of the difficulties associated with delivering andsecuring the bifurcated grafts of the prior art. By providing a graft inthe form of modular components that can be individually selected andassembled together, the present invention permits more accurate sizingof the graft to the individual patient. Moreover, the modular systemforms grafts having a fully supported structure which is much strongerthan the prior art grafts and which obviates the prior art procedures inwhich the graft is secured by hanging at the proximal neck of theaneurysm, which arrangement is prone to acute and chronic failurewhereby the graft could become displaced or collapsed. The modularsystem of the present invention further takes advantage of the flow ofblood through the individual components to lock the components to oneanother, thereby assuring a secure assembly and minimizing thepossibility of leakage.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the subject matter of the presentinvention and the various advantages thereof can be realized byreference to the following detailed description, in which reference ismade to the accompanying drawings in which:

FIG. 1 is a perspective assembled view of a modular system for forming abifurcated graft in accordance with one embodiment of the presentinvention;

FIG. 2 is an exploded, perspective view of the modular system of FIG. 1,partially broken away to reveal the stent structures in the interiorthereof;

FIGS. 3A-J are highly schematic partial cross-sectional views of anabdominal aortic aneurysm showing the sequence of steps to repair sameusing the modular system shown in FIG. 1;

FIG. 4 is a perspective assembled view of a modular system in accordancewith an alternate embodiment of the present invention;

FIGS. 5, 6 and 7 are perspective views of base members for use inconnection with modular systems in accordance with still furtherembodiments of the present invention;

FIG. 8 is a perspective view of a component of a modular system inaccordance with yet another embodiment of the present invention;

FIG. 9 is a perspective view of a delivery catheter assembly for use inconnection with the modular system shown in FIG. 1, the sheath of thedelivery catheter assembly being in the fully retracted position andbeing partially broken away to show the interior thereof; and

FIG. 10 is a cross-sectional view of the delivery catheter assemblyshown in FIG. 9, the sheath thereof being in the fully extendedposition.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the detailed description which follows, the features of the presentinvention will be described in connection with the repair of anabdominal aortic aneurysm. A typical abdominal aortic aneurysm isillustrated in FIGS. 3A-J, in which the wall of the aorta 200 isweakened and forms a bulge 202 in the region between the renal arteries204 and the point at which the aorta 200 branches into the right iliacartery 206 and left iliac artery 208. It will be appreciated, however,that the various features of the present invention may be readilyutilized to repair defects in any body lumen which branches into two ormore lumens. Indeed, the features of the present invention may beutilized to repair a variety of defects in a body lumen even where thelumen does not have branches associated with it.

Referring to FIGS. 1 and 2, there is illustrated one preferredembodiment of a modular system 100 for forming a bifurcated graft inaccordance with one aspect of the present invention. As used herein, theterm “modular” refers to the fact that system 100 includes a number ofindividual components which may be separately delivered by intraluminaltechniques to the aneurysm site and then interconnected with one anotherin situ to form the bifurcated graft. Each of the components of modularsystem 100 is a fully supported structure which provides sufficientstrength to permit the in situ construction of the bifurcated graft. Inaccordance with one embodiment hereof, modular system 100 includes aprimary graft 110, a base member 112, and first and second grafts 114and 116, respectively, all of which are fabricated as separatecomponents which may be assembled in preselected size combinationsdepending upon the arterial morphology presented by the patient.Accordingly, each of the various components is preferably provided in arange of sizes sufficient to accommodate the arterial morphology whichthe surgeon is likely to face in the vast majority of patients.

Primary graft 110 preferably includes a main tapered portion 111 and anannular sleeve 113 having a substantially uniform diameter, taperedportion 111 and sleeve 113 together defining the overall length ofprimary graft 110 between proximal end 110 a and distal end 110 b. Asused herein, the term “proximal” refers to the end of a component whichis upstream or closest to the heart, and the term “distal” refers to theend of a component which is downstream or farthest away from the heart.Primary graft 110 may be provided in a number of lengths ranging fromabout 6 cm to about 15 cm in increments of about 10 mm, and in a numberof diameters in the expanded condition ranging from about 16 mm to about36 mm at the proximal end 110 a and from about 16 mm to about 25 mm atthe distal end 110 b, both in increments of about 2 mm. Preferably,graft 110 is provided in a range of lengths from about 8 cm to about 12cm at about 10 mm increments, in a range of diameters at proximal end110 a from about 24 mm to about 36 mm in increments of about 2 mm in theexpanded condition, and with a diameter of about 22 mm in the expandedcondition at distal end 110 b. Furthermore, graft 110 may take the formof a series of two or more grafts which are shorter in length than graft110 but which can be assembled to one another in succession during thesurgical procedure described below to form a primary graft having thedesired length.

The tapered portion 111 of primary graft 110 preferably has an angle oftaper between about 2 degrees and about 15 degrees from the centerlinethereof, with an angle of taper of about 4 degrees being most preferred.It will be appreciated, of course, that the lengths and diameters ofprimary graft 110 may be provided in wider or more narrow incrementsdepending upon the size variations in the aorta which surgeonsexperience from patient to patient. Furthermore, the foregoingdimensions are for use in repairing an abdominal aneurysm; thecomponents of a modular system for repairing other body lumens thus maybe provided in different size ranges and in different increments.

Primary graft 110 desirably includes a first series of radiomarkers 118positioned around the periphery of proximal end 110 a, and a secondseries of radiomarkers 120 positioned around the periphery of distal end110 b. Such radiomarkers are conventional in the art and, when viewedunder fluoroscopy, enable the surgeon to identify and properly locatethe ends of primary graft 110 during surgical implantation. Thus,radiomarkers 118 and 120 may be formed from biocompatible metals, suchas, for example, stainless steel or platinum-iridium, which areradioopaque, or from radioopaque polymers.

Grafts 114 and 116 are similar in construction to primary graft 110.Thus, grafts 114 and 116 preferably have a generally cylindrical tubularconstruction with graft 114 having a proximal end 114 a and a distal end114 b, and graft 116 having a proximal end 116 a and a distal end 116 b.Grafts 114 and 116 may be provided in a number of lengths ranging fromabout 4 cm to about 15 cm in increments of about 10 mm, and in a numberof diameters in the expanded condition ranging from about 10 mm to about25 mm in increments of about 2 mm. Grafts 114 and 116 preferably areprovided in lengths from about 4 cm to about 8 cm in 10 mm increments,and with diameters in 2 mm increments from about 12 mm to about 16 mm inthe expanded configuration. In contrast to the tapered configuration ofprimary graft 110, grafts 114 and 116 may have a substantially uniformdiameter along their entire lengths between the proximal and distalends. However, it is contemplated that grafts 114 and 116 may have atapered configuration similar to that of graft 110, wherein the diameterof the graft may either increase or decrease from the proximal to thedistal end thereof. Such tapered grafts are particularly useful, forexample, in those situations where the aneurysmal condition extends fromthe aorta into the iliac, enabling the graft to have a larger diameterwhere it will lie in the bulged portion of the iliac and a smallerdiameter where it will lie in the normal portion of the iliac.

Grafts 114 and 116 also preferably include a series of radiomarkers attheir respective ends. Thus, graft 114 may include a first series ofradiomarkers 122 positioned along the periphery of proximal end 114 aand a second series of radiomarkers 124 positioned along the peripheryof distal end 114 b. Similarly, graft 116 may include one series ofradiomarkers 126 positioned along the periphery of proximal end 116 aand another series of radiomarkers 128 positioned along the periphery ofdistal end 116 b.

Base member 112 is a hollow generally Y-shaped structure formed by afrustoconical main body 130 which branches into two legs 132 and 134.Leg 132 may have a generally cylindrical shape with a substantiallyuniform diameter from its juncture with main body 130 to the free endthereof. Leg 134, on the other hand, defines a skirt which graduallyincreases in diameter from its juncture with main body 130 to its freeend. Opposite legs 132 and 134, main body 130 may include an annularsleeve 131 having a substantially uniform diameter, the free end ofwhich defines an inlet 136 on the proximal end of base member 112, whileoutlets 138 and 140 are defined at the free ends of legs 132 and 134,respectively. Base member 112 may be formed by the same methods,discussed in detail below, which are used to form the taper of primarygraft 110. That is, a tapered tubular “blank” may initially be wovenwith an annular sleeve 131 formed on one end. Leg 132 may then becreated by sewing upwardly from the enlarged end of the tapered portionand parallel to the wall thereof with an overlapping edge stitch. Thestitch may then be continued to form the crotch area of base member 112and then downwardly toward the enlarged end of the tapered portion andaway from the wall thereof to form leg 134. Subsequently, any excessmaterial between legs 132 and 134 may be cut away.

As with grafts 110, 114 and 116, base member 112 also may include aseries of radiomarkers for identifying its position during surgicalimplantation. Thus, one series of radiomarkers 142 may be positionedalong the periphery of the proximal end of base member 112, anotherseries of radiomarkers 144 may be positioned along the periphery of thefree end of leg 132, and a further series of radiomarkers 146 may bepositioned along the periphery of the free end of leg 134. Yet anotherseries of radiomarkers 148 may be arranged around the circumference ofleg 134 at its juncture with main body 130. Finally, base member 112 mayinclude a further single radiomarker 150 spaced distally fromradiomarkers 142 in alignment with the side of leg 134 opposite leg 132for indicating to the surgeon the rotational orientation of base member112.

Preferably, base member 112 is also provided in a range of sizes andgeometries. In that regard, the various diameters of base member 112will most preferably be sized relative to the diameters of grafts 110,114 and 116 so that the grafts and base member can be joined togetherwith a tight, secure fit. Thus, base members 112 may be provided inwhich annular sleeve 131 has a diameter in the expanded condition in arange of sizes from about 16 mm to about 25 mm in increments of about 2mm, with an expanded diameter of about 22 mm being most preferred.Sleeve 131 also may come in a range of lengths from about 2 cm to about15 cm in increments of about 10 mm. Similarly, leg 132 may have anexpanded diameter in a range of sizes from about 10 mm to about 25 mm inincrements of about 2 mm, expanded diameters from about 12 mm to about15 mm being most preferred, and a length in a range of sizes from about2 cm to about 10 cm in increments of about 10 mm. In a preferredarrangement, leg 134 may be provided with a single diameter at itsjuncture with main body 130 of basemember 112, rather than with a rangeof different diameters. In such event, graft 116 would be provided witha corresponding diameter at its proximal end 116 a, and may then taperoutwardly to the desired diameter at its distal end 116 b.Alternatively, leg 134 may be provided in a range of diameters at itsjuncture with main body 130 to correspond to the diameter of graft 116where a graft 116 having a uniform diameter within a range of diametersis employed.

As noted above, base member 112 may also be provided with differentgeometries. That is, the angle at which legs 132 and 134 project fromthe longitudinal centerline C of main body 130 may be varied toaccommodate differences in arterial morphology from one patient to thenext. Accordingly, base members 112 may be provided such that leg 132projects from centerline C at one of a number of different angles αranging from about 10 degrees to about 60 degrees, in increments ofabout 5 degrees. Similarly, base members 112 may be provided in whichleg 134 projects from centerline C at one of a number of differentangles β ranging from about 10 degrees to about 60 degrees, inincrements of about 5 degrees. Legs 132 and 134 need not project at thesame angle from longitudinal centerline C. In other words, the angles atwhich legs 132 and 134 project from main body 130 may be determinedindependently of one another so as to conform as closely as possible tothe arterial geometry of the patient. Moreover, the centerlines of legs132 and 134 need not lie in the same plane as the centerline C of mainbody 130, but may project from centerline C in a third dimension(outwardly from the page) at one of a number of different angles rangingfrom about 0 degrees to about 90 degrees, in increments of about 5degrees. While legs 132 and 134 would typically project at the sameangle from centerline C in the third dimension, this need not be thecase and base members 112 may be provided in which legs 132 and 134project at different angles from one another in the third dimension.

Each of grafts 110, 114 and 116 preferably consists of a flexible outerlayer 152 which is supported internally along substantially its entirelength by an expandable stent 154 which assumes a generally cylindricalor tapered configuration in the expanded condition, depending upon theconfiguration it is given when initially formed, and which provides thegraft with sufficient structural strength to permit the components ofmodular system 10 to be assembled to one another in situ. In the case ofprimary graft 110, stent 154 may protrude beyond the proximal end 110 athereof and include one or more barbs 156 for anchoring graft 110 to thewall of aorta 200 to assist in holding modular assembly 100 in place.Alternatively, stent 154 may occupy the exterior of grafts 110, 114 and116, with the flexible layer 152 extending longitudinally therethrough.

Outer layer 152 is preferably formed from a biocompatible materialhaving sufficient strength to withstand the surgical implantationprocedure described more fully below and to withstand the blood flow andother biomechanical forces which will be exerted on modular system 100.Such materials may include, for example, polyester materials, such asDACRON®, polytetrafluoroethylene, expanded polytetrafluoroethylene,polyester materials coated with polytetrafluoroethylene, polyurethane,expanded polyurethane and silicone. Outer layers 152 formed from wovenmaterials are preferred. To reduce the bulk and facilitate theintraluminal delivery of grafts 110, 114 and 116, outer layer 152preferably has a thickness of about 0.1 mm which is about one-third thethickness of conventional graft materials. It will be appreciated, ofcourse, that the present invention can be practiced using materialswhich are greater than 0.1 mm in thickness, including conventional graftmaterials.

Methods for forming tubular woven articles having a uniform diameter arewell known in the art and are commonly employed in fabricatingconventional grafts. Such methods may be utilized to fabricate the outerlayer 152 of grafts 114 and 116. Typical methods make use of a narrowfabric weaving loom where warp threads (i.e., those threads extending inthe longitudinal direction of the tube) and weft threads (i.e., thosethreads extending transverse to the longitudinal direction of the tube)are interlaced with one another. At the weaving station of the loom, thewarp threads are fed individually through heddles aligned transverse tothe longitudinal direction on one of four or more shafts. The upward anddownward movement of the shafts moves a preselected pattern of the warpthreads up and then down, two of the shafts moving the warp threads forforming the upper surface of the tube, and two of the shafts moving thewarp threads for forming the lower surface of the tube. As the warpthreads on one shaft are drawn upwardly and the warp threads on anothershaft are drawn downwardly, the weft thread is shuttled in a firstdirection between those groups of warp threads to weave the uppersurface of the tube. The weft thread is then shuttled in a reversedirection between another group of upwardly and downwardly drawn warpthreads to weave the lower surface of the tube. The position of theshafts and thus the position of the warp threads is then reversed andthe weft thread is again shuttled between the groups of warp threads,the process continuing to weave a tubular shape.

As they approach the weaving station, the warp threads are fed betweenthe fingers of a front reed which align the threads for weaving andwhich thus determine the ultimate shape of the woven article. Forweaving tubular articles having a substantially constant diameter, suchas outer layer 152 of grafts 114 and 116, a conventional front reedwhich is fixed in place and which has evenly spaced fingers is used toproduce constant spacing between the warp threads. Where a tubulararticle having a gradually increasing or decreasing diameter is desired,however, the conventional reed is replaced with a fan-shaped reed inwhich the spacing between the fingers is narrow at the bottom andgradually increases toward the top. Such fan-shaped reeds areconventional in the textile industry, and find use for such applicationsas weaving tapered flat camera straps. In such processes, the reeds arenot held in a fixed position, but rather are moved upward or downward toalter the diameter of the article being woven. Thus, when the fan-shapedreed is gradually moved downward as the weaving of the tube advances,the spacing between the warp threads and, hence, the diameter of thetubular article being woven will gradually be increased. Similarly, whenthe reed is gradually moved upward as the weaving of the tube advances,the spacing between the warp threads will decrease as will the diameterof the tubular article being woven. The rate of movement of the reedwill determine the taper of the article being woven; the faster the reedis moved, the larger the angle of taper, and the slower the reed ismoved, the smaller the angle of taper. Moving the reed at a constantrate will produce a constant angle of taper. However, changing the rateof movement of the reed enables tubular articles to be formed withcurved or changing angles of taper (as shown in FIGS. 7 and 8). Theupward or downward movement of the reed, and therefore the degree oftaper in the woven article, can be controlled in a known fashion by theuse of a stepping motor and a system controller.

As the space between the warp threads is increased to weave a tubulararticle with an increasing diameter, it is desirable to decrease thespacing between the weft threads so as to maintain the structuralintegrity of the article being woven. This also can be accomplished in aconventional fashion by employing a solenoid-activated mechanism towithdraw the working pawl in the conventional pawl and ratchet fabrictake off system from its normal operating position. Operation of thesolenoid can also be dictated by the system controller.

Weaving processes employing a movable fan-shaped reed can be employed toform the outer layer 152 for tapered graft 110. In such process, thefront fan-shaped reed of the loom would initially be held in a fixedupper position to weave the substantially uniform diameter tube forannular sleeve 113. When the annular sleeve 113 reaches the desiredlength, the front reed would be drawn downward at a rate which wouldproduce the desired angle of taper. The front reed would continue to bedrawn downward as the weaving process continues until a layer 152 havingthe desired tubular configuration has been formed.

Stent 154 may be formed from a wire or the like of a low shape-memorymaterial which has been bent back and forth in a curved pattern in thelongitudinal direction of the graft and then wrapped in acircumferential direction transverse to the longitudinal direction toform one or more loops of a predetermined circumference. As used herein,the term “low shape-memory material” refers to a material that, oncedeformed from an initial shape to a subsequent shape, will tend tomaintain the subsequent shape and not return to the initial shape. Suchmaterials preferably include biocompatible metals, including, forexample, stainless steel, titanium, tantalum, gold, platinum, copper andthe like, as well as alloys of these metals. Biocompatible lowshape-memory plastics may also be used to form stent 154. Alternatively,stent 154 may be formed from a high shape-memory plastic or alloy, suchas nitinol, which automatically transforms from one shape to anothershape as its temperature passes through a critical point. Whether stent154 is formed from a low shape-memory material or from a highshape-memory material is not critical, and impacts on the presentinvention predominantly in terms of the technique used to intraluminallydeliver the components of modular system 100 to the aneurysm site andfix same in place. The structure of preferred stents 154 and methods forforming same are disclosed in commonly assigned U.S. patent applicationSer. No. 08/353,066 entitled “High Hoop Strength Intraluminal Stent”,the disclosure of which is incorporated by reference herein.

Base member 112 is similar in construction to grafts 110, 114 and 116,and includes a flexible outer layer 160 which is ordinarily formed fromthe same materials as outer layer 152. An expandable generally Y-shapedstent 162 internally supports outer layer 160 along substantially itsentire length, providing structural strength thereto, and is ordinarilyformed from the same materials and by the same methods as stent 154. Aswith grafts 110, 114 and 116, base member 112 may be constructed withstent 162 on the exterior and flexible layer 160 arranged interiorthereof.

Grafts 110, 114 and 116 and base member 112 are each radially expandablefrom a collapsed condition in which the circumferences thereof areminimized so that the components can be delivered to the site of theaortic aneurysm intraluminally, to an expanded condition in which thecircumference of each of the components approaches a predeterminedmaximum circumference. As will be described more fully below, eachcomponent is normally held in the collapsed condition by the outersheath of a catheter during intraluminal delivery. Once properlylocated, the component is deployed from the catheter and radiallyexpanded until its circumference firmly contacts the interior wall ofeither the artery in which it is situated or the component to which itis being connected to hold the graft in this implanted location.

Once the proper sizes for the various components of modular system 100have been selected, the components are preferably preloaded into one ormore disposable delivery catheter assemblies which then may be used bythe surgeon to intraluminally introduce the components into the patientand to assemble same to one another in the form of a bifurcated graft.One such delivery catheter assembly 300 is shown in FIGS. 9-10. Deliverycatheter assembly 300 includes an elongated tubular outer sheath 302formed from a conventional polymer which is sufficiently flexible thatit will readily bend as catheter assembly 300 is fed through thearterial path during the intraluminal surgical procedure. Typicalmaterials for forming sheath 302 include, for example, nylon, TEFLONpolytetrafluoroethylene, polyethylene and the like. The forward end 302a of sheath 302 may include a radiomarker 304 for readily identifyingand locating end 302 a under fluoroscopy. Radiomarker 304 may take theform of an annular ring formed from a metal, such as stainless steel orplatinum-iridium, or a radioopaque polymer, or may consist of anyradioopaque material applied to the end 302 a of sheath 302. At itsrearward end 302 b, sheath 302 may include a conventional T-handle 306having finger grips 308 and a hollow stem 310.

An inner tubular member 312 is arranged in sheath 302 for slidablelongitudinal movement with respect thereto. Tubular member 312 defines acontinuous internal passageway 313 through delivery catheter 300 so thatthe delivery catheter can be assembled onto and follow a guidewireduring the intraluminal delivery procedure. In that regard, tubularmember 312 may be formed from any biocompatible material which resistskinking. In a preferred arrangement, however, tubular member 312includes a coiled, spring-like wire 314 which is flexible, yet which hassufficient radial strength to resist collapsing due to the forcesexerted by the components of modular system 100 when they are loaded indelivery catheter 300. In a highly preferred arrangement, the coil 314may be surrounded by a thin-walled polymer tube 316 or coated with animpervious polymer layer (not shown) so that medications, dyes and thelike may be supplied through passageway 313 to the abdominal aortarepair site.

At one end of coil 314, tubular member 312 includes a tip 318 which maybe formed from a biocompatible polymer, such as polyurethane, TEFLONpolytetrafluoroethylene, nylon or the like, with a conventionalradioopaque marker (not shown) formed or assembled thereon. Tip 318preferably has an outer diameter which is larger than the inner diameterof sheath 302 so that tip 318 cannot be drawn into sheath 302 as thesheath and tubular member 312 are moved relative to one another. Theforward end of tip 318 preferably has a smoothly curved surface 320 tofacilitate the forward movement of delivery catheter assembly 300through the arterial system. At its rearward end, tip 318 may include areduced diameter portion 322 sized to fit within the sheath 302 so as toaxially align tip 318 with sheath 302 in the mated condition and sealthe end 302 a of the sheath. A bore 324 in tip 318 communicates with thepassageway 313 in tubular member 312 to enable a guidewire, medication,dye and the like to exit from delivery catheter assembly 300.

At the opposite end of coil 314, tubular member 312 may include astabilizer tube 326 which extends outwardly of sheath 302 through thehollow stem 310 of T-handle 306. Stabilizer tube 326 may be formed fromany biocompatible material, including polymers such as polyurethane,TEFLON polytetrafluoroethylene and nylon, and metals, such as stainlesssteel. A thumbscrew 328 in T-handle 306 may be actuated to engagestabilizer tube 326, thereby locking tubular member 312 in place withrespect to sheath 302. Exterior of sheath 302, stabilizer tube 326 maybe fitted with a conventional hand grip 330 and any number ofconventional accessories, such as the Y-connector 332, hemostasis valve334 and stopcock 336 illustrated in FIG. 9.

A cylindrical spacer 331 formed on tubular member 312 at a spaceddistance from the rearward end of tip 318 defines a first annular cavity333 within sheath 302 for holding and delivering the first component ofmodular system 100 to be deployed during the surgical proceduredescribed below, in this case graft 114. Spacer 331 may also be formedfrom any biocompatible material, including polyurethane, TEFLONpolytetrafluoroethylene, nylon and stainless steel, and preferablyincludes a radiomarker (not shown) so that its position can beidentified by fluoroscopy during the surgical procedure. The length ofcavity 333 will depend upon the length of the particular component ofmodular system 100 to be assembled therein. Thus, cavity 333 preferablywill be sufficiently long to accommodate the component, but not so longthat there is a substantial unsupported gap between the end of thecomponent and either tip 318 or spacer 331 which may permit sheath 302to kink as a result of the axial forces applied to feed deliverycatheter assembly 300 through the arterial system.

A second spacer 335 having generally the same construction as spacer 331is formed on tubular member 312 at a spaced distance from the firstspacer 331, thus defining a second annular cavity 337 within sheath 302for holding and delivering the second component of modular system 100 tobe deployed during the surgical procedure, in this case base member 112.The length of cavity 337 will be sufficient to accommodate base member112, but not so long that there is a significant unsupported gap betweenbase member 112 and either spacer 331 or spacer 335.

Delivery catheter assembly 300 further includes a coiled, spring-likewire 340 assembled in sheath 302 between spacer 335 and the end ofstabilizer tube 326. Coil 340 radially supports sheath 302 to preventthe kinking of same and provides a structure for transferring the axialload applied through T-handle 306 to spacers 335 and 331, while at thesame time not detracting from the overall flexibility of deliverycatheter assembly 300.

A method for introducing and assembling the various components ofmodular system 100 to repair an abdominal aortic aneurysm will now bedescribed with reference to FIGS. 3A-J. The described method assumesthat the stents 154 within grafts 110, 114 and 116 and the stent 162within base member 112 are formed from a memory metal, such that thestents, and hence each of the components, will radially expandautomatically as their temperature reaches the transition temperaturefor the memory metal following deployment within the body. From themethod described hereinafter, methods employing balloon expansiontechniques for introducing and assembling the components of a modularsystem 100 in which stents 154 and 162 are formed from low shape-memorymaterials will be readily apparent to one skilled in the art.Accordingly, a detailed description of such methods is not providedherein.

Thus, in a repair method of the present invention, an arteriotomy isinitially performed on the right leg and, under conventionalfluoroscopic guidance techniques, a first guidewire 400 is introducedthrough the right femoral artery (not shown) and right iliac 206 intothe aorta 200. Delivery catheter assembly 300 containing in successiongraft 114 and base member 112 may then be assembled on guidewire 400,the guidewire being threaded through passageway 313 in tubular member312 and advanced under fluoroscopic guidance until the end 302 a ofsheath 302 is positioned adjacent the junction of right iliac 206 andaorta 200, as shown in FIG. 3A. At this point, thumbscrew 328 may beloosened and T-handle 306 of delivery catheter assembly 300 pulledbackward to partially retract sheath 302 with respect to tubular member312, thereby exposing the proximal end 114 a of graft 114 as illustratedin FIG. 3B. Sheath 302 may then be retracted further to the positionillustrated in FIG. 3C wherein the end 302 a thereof is aligned withspacer 331, at which point the first annular cavity 333 will becompletely open and the entirety of graft 114 will be exposed. Withsheath 302 no longer insulating graft 114 and retaining it in thecollapsed condition, graft 114 will expand radially as its temperatureincreases through the transition temperature of the memory metal formingthe stent 154 therein. This radial expansion will continue until theouter layer 152 of graft 114 firmly engages the interior wall of iliac206 to hold graft 114 in this implanted location.

Following deployment of graft 114, thumbscrew 328 may be tightened tolock sheath 302 relative to tubular member 312 and delivery catheterassembly 300 may be advanced as a unit into the base of aneurysm 202, asshown in FIG. 3D, until the radiomarkers 144 on leg 132 of base member112 are aligned within the proximal end 114 a of graft 114, at a spaceddistance below the radiomarkers 122. This distance should be such as toprovide a sufficient overlap between the proximal end 114 a of graft 114and the free end of leg 132 that a secure connection will be formedbetween these members. Once properly positioned, thumbscrew 328 may beloosened and the outer sheath 302 of delivery catheter assembly 300retracted relative to tubular member 312 to expose sleeve 131 on theproximal end of base member 112. At this point, the surgeon may look forthe single radiomarker 150 just inwardly of radiomarkers 142 to assurethat leg 134 of base member 112 is in alignment with left iliac 208. Ifleg 134 is not properly aligned, delivery catheter assembly 300 may berotated until such alignment is achieved. With base member 112 properlypositioned, sheath 302 may be retracted further as shown in FIG. 3Euntil the end 302 a thereof is aligned with spacer 335, whereupon thesecond annular cavity 337 will be completely open and the entirety ofbase member 112 will be exposed. Again, without sheath 302 retaining itin the collapsed condition, base member 112 will expand radially untilthe free end of leg 132 contacts and firmly engages the interior wall onthe proximal end 114 a of graft 114 in overlapping relationship. Formingleg 132 of base member 112 with a diameter in the fully expandedcondition which is larger than the fully expanded diameter of graft 114will assure that the foregoing assembly procedure securely locks basemember 112 and graft 114 together and forms a seal which prevents theleakage of blood from therebetween.

With graft 114 and base member 112 deployed and assembled together,tubular member 312 may be retracted with respect to sheath 302 until thereduced portion 322 of tip 318 is positioned within the end 302 a ofsheath 302. Thumbscrew 328 may then be tightened to lock these twoelements together and the entire delivery catheter assembly 300 may bewithdrawn from the patient, with guidewire 400 being retracted intoright iliac 206 and temporarily left in place therein. A secondarteriotomy may then be performed on the left leg of the patient and,again under fluoroscopic guidance, a second guidewire 410 may beintroduced up through the left femoral artery (not shown), through theleft iliac 208, into base member 112 through the outlet 140 defined atthe free end of leg 134, and finally out through the inlet 136 definedat the free end of sleeve 131. With guidewire 410 in place, guidewire400 may be fully withdrawn from the patient. A second delivery catheterassembly 500 containing in succession grafts 116 and 110 may then beadvanced over guidewire 410 through the left femoral artery and leftiliac 208 until the tip 518 thereof is positioned within leg 134 of basemember 112, with radiomarkers 126 on the proximal end 116 a of graft 116located a spaced distance above radiomarkers 148 on base member 112 atthe juncture of leg 134 and main body 130, all as illustrated in FIG.3F. When delivery catheter assembly 500 has been properly positioned,the thumbscrew thereon (not shown) may be loosened and sheath 502partially retracted with respect to tubular member 512, thereby exposingthe proximal end 116 a of graft 116. With sheath 502 no longer holdingthe proximal end 116 a of graft 116 in the collapsed condition, theproximal end will begin to expand radially until it contacts and firmlyengages the inner wall of base member 112 at the juncture between mainbody 130 and leg 134. Again, a secure leakproof assembly of graft 116 tobase member 112 can be obtained by assuring that the diameter of graft116 in the fully expanded condition is greater than the diameter of basemember 112 at the juncture between main body 130 and leg 134, and that asufficient portion of the proximal end 116 a of graft 116 is locatedabove this juncture. The remainder of graft 116 may then be deployed asshown in FIG. 3H by retracting sheath 502 further until the end 502 athereof is aligned with spacer 530.

Once graft 116 has been deployed, guidewire 410 may be advanced untilthe end thereof is positioned above the renal arteries 204. Thethumbscrew on delivery catheter assembly 500 may be tightened to locksheath 502 relative to tubular member 512 and the delivery catheterassembly may then be advanced over guidewire 410 to the position shownin FIG. 3H, wherein the radiomarkers 120 on the distal end 110 b ofgraft 110 are positioned within sleeve 131 of base member 112, but at aspaced distance below radiomarkers 142. When primary graft 110 has beenproperly located with respect to base member 112, i.e., with asufficient overlap between the distal end 110 b of graft 110 and theproximal end of base member 112, the thumbscrew on delivery catheterassembly 500 may be loosened and sheath 502 retracted relative totubular member 512 to expose the proximal end 110 a of graft 110. Asillustrated in FIG. 3I, with sheath 502 no longer holding it in thecollapsed condition, the proximal end 110 a of graft 110 will expandradially until the outer layer thereof firmly engages the interior wallof aorta 200. This radial expansion will also cause the barbs 156 on theproximal end of graft 110 to contact the inner wall of aorta 200.Tightening the thumbscrew thereof and then tugging slightly on deliverycatheter assembly 500 will assure that barbs 156 grab into the innerwall of aorta 200 to assist in holding primary graft 110 and, hence, theproximal end of modular system 100 in place. With barbs 156 securelyengaged, the thumbscrew may be loosened and sheath 502 retractedrelative to tubular member 512 until the tip 502 a of the sheath isaligned with spacer 534 to expose and deploy the remainder of primarygraft 110. As primary graft 110 is fully deployed, the distal end 110 bthereof will expand radially until it firmly engages the interior wallof sleeve 131, securely locking primary graft 110 to base member 112 ina leakproof arrangement. Tubular member 512 may then be retractedrelative to sheath 502 until the reduced diameter portion 522 of its tip518 is positioned within the end 502 a of the sheath. Tubular member 512may then be locked to sheath 502 by tightening the thumbscrew ofdelivery catheter assembly 500, and the entire assembly may be withdrawnfrom the patient. Subsequently, guidewire 410 may be withdrawn from thepatient and the arteriotomies sutured.

Once deployed and assembled together according to the foregoingprocedure, the components of modular system 100 form a bifurcated graftwhich is fully self supporting. That is, as a result of its bottom-upassembly, the biomechanical forces exerted on the graft, particularlyfrom the flow of blood, are supported along its entire length in acolumnar fashion.

It will be appreciated, of course, that variations in the foregoingprocedure can be made without departing from the scope of the presentinvention. For example, delivery catheter assembly 300 may be fabricatedwith three spacers defining three annular cavities in succession, withgraft 114 loaded in the first annular cavity, base member 112 loaded inthe second annular cavity and primary graft 110 loaded in the thirdannular cavity. In such event, graft 114 and base member 112 may bedeployed in succession as described above, following which the deliverycatheter assembly may be advanced to deploy primary graft 110.Subsequently, graft 116 would be deployed and assembled to base member112 as described above utilizing a second delivery catheter assemblyhaving only one spacer defining a single annular cavity for holdinggraft 116.

Other variations from the foregoing method are also possible. In thisregard, rather than relying merely upon the outward radial forcesexerted by the expanding stent structures of grafts 110 and 116 and basemember 112 to securely lock the components together, the appropriateends of these components may be provided with mechanical structures,such as barbs, sutures and the like, to assure that the components aresecurely held together.

By changing the configuration of the various components of the modularsystem, still other variations in the surgical procedure are possible.Thus, referring to FIG. 4, the modular system may include a base member550 having an integral elongated leg 552. Leg 552 would typically beformed with a substantially uniform diameter and a sufficient lengththat at least the distal end 554 thereof will securely engage rightiliac 206 upon the deployment of base member 550, thereby eliminatingthe need to deploy a separate graft in right iliac 206 and connect thebase member thereto, as in the case with graft 114 and base member 112described above. As a result, the use of base member 550 results in asimpler surgical procedure while maintaining substantially all of theadvantages associated with the modular system 100 of the presentinvention.

Furthermore, the base member need not have integrally formed legsdepending distally therefrom. For example, in accordance with anotherembodiment of the present invention, the modular system may include abase member 600 such as shown in FIG. 5. Base member 600 has a generallyfrustoconical main body 602 which gradually decreases in diameter fromthe distal end 600 b of the base member to its juncture with an annularsleeve 604. Sleeve 604 has a substantially uniform diameter until itsterminus at the proximal end 600 a of base member 600. The main body 602of base member 600 is divided into two portions 606 and 608 by a web 610which extends from the distal end 600 b of the base member to thejuncture between main body 602 and sleeve 604. Web 610 is connectedwithin base member 600, such as by sewing, heat welding or the like, soas to define a substantially circular opening 612 on one side of thedistal end 600 b of base member 600, and another substantially circularopening 614 on the other side of base member 600 at the juncture betweenmain body 602 and annular sleeve 604. The diameter of opening 612 ispreferably large enough to readily accept the proximal end 116 a ofgraft 116, but not so large as to interfere with the insertion of theproximal end 114 a of graft 114 into the remaining crescent-shapedopening 616 at the distal end 600 b of base member 600. Hence, thediameter of opening 612 is preferably between about one half and threequarters of the diameter of base member 600 at its distal end. As foropening 614, it preferably has a diameter which is smaller than thefully expanded diameter of graft 114 at its proximal end 114 a.

As with the components of modular system 100 described above, basemember 600 preferably consists of a flexible outer layer 618 which issupported internally along substantially its entire length by anexpandable stent 620. In a preferred arrangement, web 610 is connectedwithin base member 600 after stent 620 has been placed within outerlayer 618.

Base member 600 may also be provided with a plurality of radiomarkersfor locating the various regions thereof under fluoroscopy. Thus, basemember 600 may include one series of radiomarkers 619 around theperiphery of proximal end 600 a, another series of radiomarkers 621around the periphery of distal end 600 b, and another series ofradiomarkers 622 formed around the periphery of base member 600 at thejuncture between main body 602 and annular sleeve 604. A further singleradiomarker 624 may be positioned distally of radiomarkers 622 inalignment with the side of base member 600 opposite opening 614 forindicating the rotational orientation of the base member.

The procedure for implanting and assembling a modular systemincorporating base member 600 is different from that described abovewhere the modular system utilizes base member 112. More particularly,rather than deploying and assembling the components from the bottom upas described above, when a base member 600 is utilized the componentsare deployed and assembled from the top down. That is, the primary graft110 would be the first component deployed followed by base member 600.In this procedure, however, rather than inserting and expanding thedistal end 110 b of primary graft 110 within the proximal end of thebase member to join these components together, just the oppositeprocedure is performed. In other words, once primary graft 110 has beendeployed, base member 600 would be deployed so that its proximal end 600a is inserted into and expands within the distal end 110 b of primarygraft 110. Subsequently, graft 116 may be fed upwardly until itsproximal end 116 a enters base member 600 through opening 612. With theproximal end 116 a of graft 116 positioned at a spaced distance aboveopening 612 (as determined by radiomarkers appropriately placed on thecomponents), graft 116 may be deployed whereupon it will become securelylocked within portion 608 of base member 600, with the substantiallycircular periphery of graft 116 sealing against the substantiallycircular periphery of opening 612 to prevent the leakage of bloodtherebetween. As it radially expands, the distal end 116 b of graft 116will engage and become secured within left iliac 208. Graft 110, basemember 600 and graft 116 may be deployed in succession from a singledelivery catheter assembly similar in construction to delivery catheterassembly 300, yet having a series of three annular cavities. A seconddelivery catheter assembly may be fed through crescent-shaped opening616 in base member 600 and then upwardly therefrom to position theproximal end 114 a of graft 114 at a spaced distance above opening 614(also as determined by appropriately placed radiomarkers). Upondeployment of graft 114 in this position, the substantially circularperiphery thereof will firmly engage the substantially circularperiphery of opening 614 to similarly seal against the leakage of bloodfrom therebetween. The distal end 114 b of graft 114, as it radiallyexpands, will engage and become secured within right iliac 206.

In a variant of the foregoing embodiment, the base member may be formedwith the general shape of base member 600, but without the internal web610. A base member 650 in accordance with this embodiment is illustratedin FIG. 6. Base member 650 is intended to be used in those situations inwhich the modular system is to be assembled with no iliac grafts 114 and116. Thus, the modular system would include primary graft 110 and basemember 650 which may be deployed either as described immediately abovein connection with base member 600 (i.e., primary graft 110 firstfollowed by base member 650), or as described previously in connectionwith base member 112 (i.e., base member 650 first followed by primarygraft 110). However, in positioning base member 650, the surgeon wouldensure not only that the proximal end 650 a of base member 650 willoverlap with the distal end 110 b of graft 110, but also that the distalend 650 b of base member 650 will lie against the apex between iliacs206 and 208, whereby the arterial wall at the apex may support themodular system in its fully deployed and assembled condition. In thisscenario, blood flow into graft 110 and through base member 650 willdivide at the apex as it exits from the distal end 650 b of the basemember and will flow into both the right iliac 206 and left iliac 208.

A still further embodiment of a base member 700 in accordance with thepresent invention is shown in FIG. 7. In one region 702 extending fromproximal end 700 a along a major portion of its length, base member 700has a substantially uniform diameter. The diameter of base member 700then gradually increases in a second region 704 thereof until itsterminus at distal end 700 b. Tapered region 704 may be formed by thesame methods used to form the taper of primary graft 110, as discussedmore fully above.

Base member 700 further includes a stitch line 706 which extends in thelongitudinal direction thereof within region 702, the stitch linejoining the outer layer 708 on the diametrically opposed surfaces ofbase member 700 to define two tubular channels 710 and 712 intermediateproximal end 700 a and distal end 700 b. As with the other components ofthe modular systems described above, the outer layer 708 of base member700 is supported internally along substantially its entire length by anexpandable stent 714. In that regard, stent 714 may consist of anassembly of several members which independently support tapered region704, tubular channels 710 and 712, and the proximal end of base member700. Base member 700 may also be provided with radiomarkers, includingone series of radiomarkers 716 formed around the periphery of proximalend 700 a, another series of radiomarkers 718 formed around theperiphery of distal end 700 b, and another series of radiomarkers 720formed around the periphery of the base member at the distal end ofstitch line 706. In addition, base member 700 may include a furthersingle radiomarker 722 spaced distally of radiomarkers 716 in alignmentwith the side of tubular channel 712 opposite tubular channel 710 forindicating the rotational orientation of the base member.

In a variant of this embodiment, tubular channels 710 and 712 mayconsist of tubes of substantially uniform diameter which are independentof one another. Such embodiment would look similar to base member 700 asillustrated in FIG. 7, but would have an elongated through hole in placeof stitch line 706. Such embodiment may be formed, for example, from twodevices having a tapered region (as at 704) and two tubular legsextending from the tapered region, one device being inverted relative tothe other and the devices being joined to one another at their tubularlegs.

One procedure for implanting and assembling a modular systemincorporating base member 700 may be similar to that described above inconnection with base member 600. That is, the primary graft 110 would bedeployed first, following which base member 700 may be deployed with itsproximal end 700 a inserted into and expanded within the distal end 110b of primary graft 110. Graft 114 may then be fed upwardly until itsproximal end 114 a resides within tubular channel 710 at a spaceddistance above radiomarkers 720. Upon its deployment, the proximal end114 a of graft 114 will become securely locked within tubular channel710 and the distal end 114 b thereof will engage and become securedwithin right iliac 206. Graft 116 may then be fed upwardly until itsproximal end 116 a lies within tubular channel 712 at a spaced distanceabove radiomarkers 720. Upon deployment of graft 116, the proximal end116 a thereof will become securely locked within tubular channel 712 andthe distal end 116 b thereof will engage and become secured within leftiliac 208. It will be appreciated from the foregoing that graft 110,base member 700 and graft 114 may be deployed in succession from a firstdelivery catheter assembly, with graft 116 being deployed from a seconddelivery catheter assembly. In an alternate procedure employing basemember 700, the base member may be deployed first, followed insuccession by grafts 110, 114 and 116.

In a variant of the foregoing embodiment, base member 700 and graft 110may be combined as a single component 750, illustrated in FIG. B.Component 750 thus may include a bottom portion 752 which hassubstantially the same structure as base member 700 described above,including a region 754 having a substantially uniform diameter, a region756 which gradually increases in diameter as it approaches the distalend 750 b of component 750, and a stitch line 758 which defines twotubular channels 760 and 762 within component 750. At its upper end,component 750 includes an integrally formed region 764 which begins witha substantially uniform diameter and which gradually increases indiameter as it approaches the proximal end 750 a thereof. Formingportions 752 and 764 as a single integral unit thus eliminates the needto deploy a separate graft 110 within aorta 200 and connect the basemember thereto. As a result, modular systems incorporating component 750provide all of the advantages of the present invention while allowingfor a simpler surgical procedure.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

We claim:
 1. A modular endovascular graft for repairing an aorticaneurysm, comprising: a base member adapted for placement within theaorta, the base member having an inferior end and a superior end; aprimary tubular limb having an inferior end and a superior end; ajoining structure that joins the superior end of the primary limb to theinferior end of the base member; one secondary tubular limb having aninferior end and a superior end; a connecting structure that connectsthe inferior end of the one secondary limb to the superior end of thebase member; another secondary tubular limb having an inferior end and asuperior end; and an attachment structure that attaches the inferior endof the another secondary limb to the superior end of the base member. 2.The graft of claim 1, wherein the base member can assume a collapsedconfiguration and an expanded configuration.
 3. The graft of claim 2,wherein the primary tubular limb can assume a collapsed configurationand an expanded configuration.
 4. The graft of claim 1, wherein the onesecondary limb can assume a collapsed configuration and an expandedconfiguration.
 5. The graft of claim 1, wherein the another secondarytubular limb can assume a collapsed configuration and an expandedconfiguration.
 6. The graft of claim 1, wherein the another secondarylimb has a substantially uniform diameter.
 7. The graft of claim 1,wherein the another secondary limb has a first diameter at the inferiorend and a second diameter at the superior end different than the firstdiameter.